Polyamide containing oxidized polyethylene



United States Patent 3,262,989 PULYAMTDE QONTAHNHNG QXHDIZED POLYETHYLENE Edmond P. Brignac, Pensacola, Fla, assignor to Monsanto Company, a corporation of Delaware No Drawing. Filed Get. 11, 1962, Ser. No. 229,967 4 Claims. (Cl. 260-857) This invention relates to a new and novel polyamide and more particularly to a new fiber-forming polyamide for making yarns and fibers which are more durable and more resistant to wet and dry abrasion and tension flexing.

A wide variety of polyamides have been described in prior patents and other publications, and the properties of these have varied widely from soft tacky materials to hard high melt products. In recent years, continuous synthetic filament yarns drawn from polyamide compounds have come into use in the manufacture of rope, cordage, tire cord and the like because of their high filament strength. The strength of such items depends largely upon the combined strength of the individual filaments which go to make up the rope, tire cord and the like, and, as is well known, excessive breakage of these filaments tends to reduce the strength and shorten the useful life of the items of which they form a part. Tire cord, heavy duty ropes such as marine howsers, and similar items quite frequently are subjected to severe stresses in tension and abrasion. When undergoing such severe stresses the continuous synthetic filaments within the cords or ropes are subjected to severe filament to filament friction mainly because of the twist in the filaments in the cord or rope which is necessary to maintain the integrity thereof. In the case of polyamide filaments especially, filament to filament friction upon many occasions may be so severe as to cause contact temperatures which are sufficient to soften or damage the filaments at and adjacent to the points of friction contact. Under such conditions, ropes or cords prepared from continuous polyamide filaments are known to fuzz and to break without utilization of the known inherent high strength properties of such filaments. Much Work has been done in the past'to prepare filaments which can be used successfully under excessive conditions of tension and abrasion in both wet and dry atmospheres, but to date this work has met only with partial success in the development of coatings and like exterior substances which are applied only to the outer surface of the fibers or cords. These coating materials are not only expensive to prepare and apply but are also effective only for short periods of time due to their easy removal by wear or solvents such as water or other with which the cords or ropes may come into contact.

It is therefore an object of the present invention to provide a novel polyamide polymer.

It is another object of this invention to provide a novel polyamide polymer suitable for the preparation of ropes or cords requiring high strength in tension and abrasion resistance.

A further object of this invention is to provide a novel polyamide polymer for the preparation of ropes, cords or like items, the filaments of which do not require a coating.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described and various other advantages not referred to herein will occur to one skilled in the art on employment of the invention as described and claimed.

The objects of this invention are accomplished by adding to polyamide forming reactants, at any time prior to the completion of their polyamide forming reaction or prior to the preparation of films and fibers from the polyamide material, from 0.1 percent to 5 percent by weight of the reactants of a partially oxidized low molecular weight polyethylene polymer capable of forming an emulsion in aqueous solutions.

The polyamide forming reactants may be of any of the Well known materials suitable for making a polyamide polymer capable of being spun or drawn into fibers or filaments and may comprise a mixture of organic primary or secondary diamine and dibasic carboxylic acid, salt thereof, or a polymarizable monoamino organic acid.

The partially oxidized low molecular weight polyethylene polymer may be any type capable of forming an emulsion in aqueous solution and having properties which are within the limits shown in Table 1 which follows.

Table 1 PROPERTIES OF PARTIALLY OXIDIZED LOW MOLECU- LAR WEIGHT POLYETHYLENE POLYMER Molecular weight (approx. number aver- Many polyamide forming processes are Well known and used to prepare polyamides having properties which include film and fiber forming properties and any of these, as well as others, may be used to prepare the new polyamide of this invention. These processses may be either batch type or continuous and comprise those wherein the polyamide forming reactants are mixed in substantially equal proportions in an aqueous or other solvent solution and then the reactant solution is subjected to the superatmospheric pressures and polyamide forming temperatures to cause the polycondensation of the polyamide reactants to proceed to the desired degree of completion.

The partially oxidized low molecular weight polyethylene polymer capable of forming aqueous emulsions may be added to the polyamide forming reactants prior to or during their mixing, at any time during the polycondensation thereof, or after the poly condensation thereof but prior to the preparation of films or fibers therefrom.

Any means for dispersing the partially oxidized low molecular weight polyethylene polymer with reasonable uniformity in the polyamide is suitable and may include the simple and well known method of mixing two materials, normally solids at rooms temperature, by melting and stirring.

The invention will be more fully understood from the following specific examples which are intended for illustration only and should not be construed by any means for limitation.

EXAMPLE I A 50 percent water solution of substantially equal quantities of hexamethylenediamine and adipic acid was prepared and mixed and then this water solution of the reactants was subjected first to evaporating conditions at 137 C. and 13 psig. for approximately 30 minutes and then to reacting conditions of 220 C. to 280 C. and 250 p.s.i.g. for approximately 90 minutes. Following this, the partially polymerized reactant solution was subjected to flashing conditions of atmosphere pressure while the temperature of the reactants was maintained at 280 C. The final step in the polymerization was accomplished by holding the partially polymerized reactants at 280 C. and atmospheric pressure in a standard autoclave for approximately 40 minutes until a relative viscosity of 44 to 46 for the polyamide polymer was obtained. This polymer was then extruded into a ribbon, cooled to approximately 40 C. with quenching water, and chipped into polyamide flake of a size well known in industry.

To a part of the polyamide flake thus prepared, 3 percent by weight of a partially oxidized granular polyethylene polymer, sold under the trademark Epolene (registered trademark of Eastman Kodak Company for its polyethylene resins) and having the grade designation E-10, was blended in a double-cone mixer until an essentially homogeneous mixture was obtained. The E- Epolene polyethylene had the physical properties shown in Table 2 below.

Table 2 Molecular weight (approx. number average) 2500 Density 0.938 Ring and ball softening point, C. (ASTM D-3626) 105 to 109 Acid number 9 to 12 saponification number 24 to 25 The blended mixture of partially oxidized polyethylene polymer and polyamide polymer was charged to a conventional synthetic fiber melt spinning machine where the polymer mixture was melted at approximately 287 C. in a steam atmosphere, extruded through a 140 orifice spinneret, and drawn into a yarn having 840 denier for each group of 140 filaments.

The yarn thus prepared was plied and twisted to strands and laid to form a one-half inch diameter rope.

For comparison test results one-half inch diameter rope was prepared in an identical manner from the polyamide chips prepared previously and with which partially oxidized polyethylene polymer was not blended.

The ropes thus prepared were subjected, both wet and dry, to identical physical property and abrasion tests, and the comparison of the results obtained are shown in Table 3 below.

A 50 percent water solution of substantially equal quantities of hexamethylenediamine and adipic acid was prepared as in Example I and then this water solution of the reactants was subjected to evaporating conditions of 137 C. and 13 pounds per square inch for approximately 30 minutes. The evaporated water solution of the reactants was then subjected to reacting conditions of 220280 C. and 250 pounds per square inch. As soon as reacting conditions were reached in the evaporated water solution, 2 percent by weight of the partially oxidized granular polyethylene polymer, sold under the trademark Epolene (registered trademark of Eastman Kodak Company for its polyethylene resins) and having the grade designation E-l0, was added to the evaporated water solution of the reactants. This mixture was subjected to the reacting conditions described previously for approximately minutes, and following this the partially polymerized reactant solution was subjected to flashing conditions of atmosphere pressure while the temperature of the reactants was maintained at 280 C. The final step in the polymerization and the preparation of the one-half inch diameter rope was accomplished as in Example I and the rope thus prepared was subjected both wet and dry to physical property and abrasion tests. A comparison of the results obtained from the tests of the rope both with and without polyethylene are shown below in Table 4.

It can be seen clearly from the above examples that there is noticeable improvement in abrasion resistance both wet and dry and retained wet strength of the rope when partially oxidized polyethylene polymer is added to the nylon polymer. This is true both when the partially oxidized polyethylene polymer is added during the polymerization process and subsequent to the polymerization process but prior to the forming of fibers.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

What is claimed is:

1. A process for preparing polyamide polymer having increased abrasion resistance comprising, in combination, the steps of:

(a) substantially homogeneously mixing polyhexamethylene adipamide and from 0.1% to 5.0%, by weight of said polyhexamethylene adipamide, of partially oxidized polyethylene polymer having a number average molecular Weight of 1,000 to 3,000, an acid number of 9 to 16, and a saponification number of 24 to 30; and

(b) melt-extruding resulting substantially homogeneously mixed material into desired form for subsequent use.

2. A polyamide polymer for forming fibers which have improved abrasion resistance and tension wet strength which comprises polyhexamethylene adipamide and from 0.1% to 5.0%, by weight of said polyhexamethylene adipamide, of partially oxidized polyethylene polymer having a number average molecular weight of 1,000 to 3,000, an acid number of 9 to 16, and a saponification number of 24 to 30.

3. A polyamide polymer yarn which has improved abrasion resistance and tension wet strength which comprises polyhexamethylene adipamide and from 0.1% to 5.0%, by weight of said polyhexamethylene adipamide, of partially oxidized polyethylene polymer having a number average molecular weight of 1,000 to 3,000, an

6 a3 acid number of 9 to 16, and a saponification number of References Cited by the Examiner 24 to 30 N D T P 4. A polyamide polymer rope which has improved U ITE STA ES ATENTS abrasion resistance and tension wet strength which com- 2,890,125 6/1959 Mange 7 260-23 prises polymerized polyhexamethylene adipamide and 5 3,093,255 6/1963 Mesroblan et a1 260-857 from 0.1% to 5.0% by weight of said polyhexamethylene adipamide of partially oxidized polyethylene polymer MURRAY TILLMAN Exammer' having a number average molecular weight of 1,000 to WILLIAM H. SHORT, Examiner.

3,000, an acid number of 9 to 16, and a saponification I W SANNER Assistant Examiner number of 24 to 30. 10 

1. A PROCESS FOR PREPARING POLYAMIDE POLYMER HAVING INCREASED ABRASION RESISTANCE COMPRISING, IN COMBINATION, THE STEPS OF: (A) SUBSTANTIALLY HOMOGENOUSLY MIXING POLYHEXAMETHYLENE ADIPAMIDE AND FROM 0.1% TO 5.0%, BY WEIGHT OF SAID POLYHEXAMETHYLENE ADIPAMIDE, OF PARTIALLY OXIDIZED POLYETHYLENE POLYMER HAVING A NUMBER AVERAGE MOLECULAR WEIGHT OF 1,000 TO 3,000, AN ACID NUMBER OF 9 TO 16, AND A SAPONIFICATION NUMBER OF 24 TO 30; AND (B) MELT-EXTRUDING RESULTING SUBSTANTIALLY HOMOGENEOUSLY MIXED MATERIAL INTO DESIRED FORM FOR SUBSEQUENTLY USE. 